Evidence emerging from a small-scale study of 360 people carried out by Prof Kakabadse and her colleagues suggested up to a third were addicted.

People could become addicted to just about anything, she said.

"We are creatures of habit and we can get addicted to quite unusual things.

"Technology has become much more interesting over the past 10 years with the internet and everything.

"It is much simpler and much more portable which makes it more accessible.

"You would be surprised how many people had their PDA or Blackberry next to their bed heads."

She added: "Those who are addicted will get up in the middle of the night and pick up messages on their PDAs two or three times a night."

'Too late'

The addiction could also lead to problems with relationships as the addict became more and more withdrawn from their family.

And there were other social consequences as the addict suffered from anxieties and sicknesses, she said.

Prof Kakabadse said in the early stages of addiction, workers were often very productive, replying to e-mails and messages, but as time went on there were more serious consequences.

"Some people are very anxious when they don't have their technological gadgets next to them.

"They might get into trouble with their employers as they spend more and more time checking messages."

She said it was often difficult to detect when someone had become an addict, "And when it is detectable it is often too late".

She stopped short of calling for warnings to be put on all gadgets, but said employers should provide training on the safe use of technological devices they provided to their staff.

Prof Kakabadse has looked in detail at case studies but now intends to see how widespread the problem is.